1. Field of the Invention
The present invention relates generally to the natural gas and petroleum industry. More specifically, the present invention relates to a mechanism for automatically and safely dispensing chemical sticks (e.g., soap or detergent sticks, etc.) into a pressurized gas well, to provide certain advantages in gas production.
2. Description of the Related Art
Gas wells generally produce natural gas by means of subterranean pressures, which force the gas to the surface of the drilled well. However, the subterranean gas within a well is always adulterated with various other substances which often interfere with the flow of gas from the well. The most common of these foreign substances is water, which can accumulate in the well bore to such an extent that it produces an overpressure that prevents the gas from coming out of solution and percolating to the top of the well, a condition known as a “drowned well.” Other conditions can occur with gas and oil wells which impede or preclude fluid flow, damage equipment and pipe within the well, and/or create other problems.
As a result, various treatments have been developed for correcting these problems from the surface. In the case of gas wells, the most common problem is water infiltration into the subterranean gas well bore, as noted above. A successful treatment of this problem has been developed, in which surfactants or “soap sticks” are dropped down the wellhead to dissolve within the well. The surfactant results in foaming of the water and gas mixture, breaking up the water so the gas may penetrate from below to escape from the well. This can increase gas production significantly from an otherwise unproductive “drowned” well. Other chemical sticks for treating other problems may also be introduced into the well from the wellhead, as required.
Conventionally, chemical sticks are generally manually dropped into the well through a series of sequentially actuated valves at the top of the wellhead, or by means of an automated machine located at the top of the well. In either case a worker must climb to the top of the wellhead, either to manually operate the valves to allow the insertion of a chemical stick into the wellhead, or at least to periodically reload an automated dispenser situated at the top of the wellhead. Climbing a ladder to the top of the wellhead perhaps ten or more feet above the surface with a relatively heavy load of chemical sticks, perhaps in a relatively high wind, snow, ice, or some other adverse condition, offers less than perfect safety, to say the least.
As a result, the present inventors developed an automated chemical stick dispenser which delivers sticks to the top of the wellhead from an automated dispenser on the surface, with the dispenser being easily reloaded as required from the surface. This has proven to be a major improvement in well maintenance safety, as the field worker need not climb to the top of the wellhead to service the stick dispenser during normal operation of the device. However, the machine previously developed by the present inventors operates in an entirely different manner from the present invention, utilizing a movable launch tube which is hinged to the top of the wellhead. Other differences are also present between the two machines, as described in detail further below.
The present invention overcomes the problems resulting from wellhead mounted stick dispensing devices by providing a ground-based dispenser which may be serviced by personnel from the ground during normal operations, rather than requiring them to climb a ladder in perhaps adverse conditions to service the dispenser. Moreover, the present machine has no externally disposed major moving components, as does the machine previously developed by the present inventors. Accordingly, the present chemical stick dispenser provides greater reliability and lower service requirements and costs of operation, as well as greater safety for field personnel, than machines of the prior art.
A discussion of the related art of which the present inventors are aware, and its differences and distinctions from the present invention, is provided below.
U.S. Pat. No. 3,403,729 issued on Oct. 1, 1968 to Charles J. Hickey, titled “Apparatus Useful For Treating Wells,” describes a manually actuated mechanical device for injecting resilient sealing balls into a pipe in a well bore. The balls block certain perforations in the pipe, to prevent pressure loss therethrough during substrate fracturing operations. The Hickey apparatus is primarily directed to providing an accurate count of the balls dispensed. The Hickey apparatus does not provide for any form of automated and/or pneumatically powered operation, as it is intended to be operated only infrequently when subterranean fracturing of the substrate around a well is required. No means of automatically delivering elongate chemical sticks from a surface-dispensing machine to the top of the wellhead is provided by Hickey.
U.S. Pat. No. 4,785,880 issued on Nov. 22, 1988 to Robert Ashton, titled “Apparatus For Dispensing Chemicals Into Oil And Gas Wells,” describes an automated stick dispenser having a cylindrical or carousel configuration, mounted atop the wellhead. The device is mechanically operated, rather than using pneumatic power from the pressure of the gas well, as in the present invention. Most importantly, the Ashton device can only be serviced by climbing to the top of the wellhead, whereas the present stick loader is serviced and replenished from the ground.
U.S. Pat. No. 4,929,138 issued on May 29, 1990 to Kurt Breuning, titled “Device For Feeding Rodlike Workpieces,” describes a machine having a sloped feeding tray in which the rods are disposed in a side-by-side array and roll downwardly toward a handling mechanism comprising a pair of wheels which grip the rods in channels therebetween. The rods roll inwardly toward the handling mechanism, rather than being propelled from the handling mechanism to a conveyor or dispensing tube, as in the present invention. Moreover, the chemical sticks handled by the present invention are transferred linearly, end-to-end up the transfer tube after being dispensed from their side-by-side array in the conveyor within the dispensing portion of the present apparatus. In any event, the Breuning device is not related to any apparatus for handling chemical sticks for insertion into a wellhead.
U.S. Pat. No. 5,188,178 issued on Feb. 23, 1993 to Jonathan C. Noyes, titled “Method And Apparatus For Automatic Well Stimulation,” describes another carousel-type stick feeder disposed at the top of the wellhead, similar to the device of the Ashton '880 U.S. patent discussed further above. The same points raised in the discussion of the Ashton device are seen to apply here as well.
U.S. Pat. No. 5,813,455 issued on Sep. 29, 1988 to Gary V. Pratt et al., titled “Chemical Dispensing System,” describes an automated chemical stick dispenser comprising an elongate magazine in which the sticks are stacked vertically, end-to-end. The device is hinged to the top of the wellhead, and pivoted from its hinge attachment to lower its distal end to the surface for loading. The device is then pivoted back into place above the wellhead for operation. While the device can be loaded from the surface, it does not rest upon the surface to propel the chemical sticks upwardly through a transfer tube or the like, as in the case of the present invention.
U.S. Pat. No. 6,039,122 issued on Mar. 21, 2000 to Leonel Gonzalez, titled “Methods And Apparatus For Automatically Launching Sticks Of Various Materials Into Oil And Gas Wells,” describes another carousel-type stick loading magazine atop a gas well. This device simplifies the system, by eliminating the valves between the well and the carousel magazine. The magazine is pressurized to prevent gas from escaping from the system. The well is closed off whenever the magazine must be opened for reloading. This system adds to the danger of servicing or reloading a wellhead top mounted system, not only due to the height, but also due to the pressurized gas contained within the magazine.
U.S. Pat. No. 6,044,905 issued on Apr. 4, 2000 to William G. Harrison III, titled “Chemical Stick Storage And Delivery System,” describes yet another carousel type system placed atop the wellhead. The valves are hydraulically actuated rather than using the pneumatic principle by means of gas pressure from the well, as in the present invention.
U.S. Pat. No. 6,056,058 issued on May 2, 2000 to Leonel Gonzalez, titled “Methods And Apparatus For Automatically Launching Sticks Of Various Materials Into Oil And Gas Wells,” is the parent of a divisional application from which the '122 U.S. patent to the same inventor issued, the '122 reference being discussed further above. The same points noted in that discussion are seen to apply here as well.
U.S. Pat. No. 6,269,875 issued on Aug. 7, 2001 to William G. Harrison III et al., titled “Chemical Stick Storage And Delivery System,” is a continuation-in-part of the application resulting in the issued '905 U.S. patent described further above. The primary difference between the two devices is the use of a central processing unit to control the release of the chemical sticks in the system of the '875 patent, whereas the earlier issued '905 U.S. patent discloses only the use of a timer. Both provide a stick dispenser or magazine disposed atop the wellhead, unlike the present invention.
U.S. Pat. No. 6,283,202 issued on Sep. 4, 2001 to Gene Gaines, titled “Apparatus For Dispensing A Chemical Additive Into A Well,” describes a dispenser mounted atop the wellhead, with the dispenser holding only a single chemical stick. While a timer and actuating mechanism are provided for automatically releasing the stick, no means is provided for sequentially dispensing a series of chemical sticks into the well over a period of time, as provided by the present invention.
U.S. Patent Publication No. 2002/129,941 published on Sep. 19, 2002 and applied for by Lee Alves et al., titled “Automatic Chemical Stick Loader For Wells And Method Of Loading,” describes a system having a ground-based stick storage magazine and dispenser, with an elongate delivery tube movably extending between the storage magazine and the top of the wellhead. Rather than being fixed between the magazine and the top of the wellhead, as in the present invention, the system of the '941 U.S. Patent Publication automatically and selectively moves one end of the delivery tube between a lowered position communicating with the stick dispenser magazine, where it receives a single chemical stick, and a raised position with the magazine dispenser end of the tube raised generally vertically above the wellhead. The wellhead end of the tube remains pivotally attached to the wellhead at all times. In contrast, the stick delivery tube extending between the dispensing cabinet or magazine and the top of the wellhead in the present invention remains fixed in place at all times; there are no external moving parts or components in the present system. The '941 U.S. Patent Publication also discloses the use of solar power for the electrical energy required to operate the system, the use of pneumatic power from the pressure of the gas well to operate the pneumatic devices of the system, and the use of a programmable electronic controller for actuating the device according to time interval, weather, well conditions, etc., which features are all hereby incorporated by reference into the present application.
U.S. Pat. No. 6,478,089 issued on Nov. 12, 2002 to Lee Alves et al., titled “Automatic Chemical Stick Loader For Wells And Method Of Loading,” is the issued U.S. patent based upon the '941 U.S. Patent Publication discussed immediately above. The same points noted in that discussion are seen to apply to the '089 U.S. patent to the same inventors, as well.
U.S. Patent Publication No. 2003/10,504 published on Jan. 16, 2003 and applied for by Dan Casey, titled “Soap Stick Launcher And Method For Launching Soap Sticks,” describes a device having a stick dispensing canister or magazine disposed at the top of the wellhead, and pressurized by well gas. As such, the Casey device is more closely related to the device of the '122 and '058 U.S. patents to Gonzalez, discussed further above, than it is to the present invention.
U.S. Pat. No. 6,637,512 issued on Oct. 28, 2003 to Dan Casey, titled “Soap Stick Launcher And Method For Launching Soap Sticks,” is the issued U.S. patent based upon the '502 U.S. Patent Publication discussed immediately above. The same points noted in the discussion of the '502 U.S. Patent Publication are seen to apply here as well.
Finally, German Patent No. 3,528,743 published on Feb. 12, 1987, titled “Device For Feeding Rodlike Workpieces,” is the German Patent Publication upon which the '138 U.S. patent to the same inventor, discussed further above, is based. The same points noted in that discussion are seen to apply here as well.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed. Thus an automated chemical stick loader for gas wells, and a method of automatically loading chemical sticks into a gas well, solving the aforementioned problems is desired.